Not applicable.
Not applicable.
1. Field of the Invention
The present invention relates to macrocycles having three naphthyridine subunits and salts and metal complexes thereof; to a process for the preparation of these macrocycles, their salts and complexes; and to the use of compositions of these macrocycles for extracting a transition metal and a method for extracting a transition metal using the composition.
2. Background Art
The transition metals include the nine metals of Group VIII of the periodic table, as representative examples thereof, and the lanthanide and actinide metals. The transition metals further include the metals called rare metals, noble metals, and heavy metals. Specific examples thereof include iron (Fe), cobalt (Co), nickel (Ni), ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), copper (Cu), zinc (Zn), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), silver (Ag), cadmium (Cd), lanthanum (La), cerium (Ca), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), hafnium (Hf), tantalum (Ta), tungsten (W), gold (Au), mercury (Hg), uranium (U), and plutonium (Pu). These transition metals are used not only in catalysts and iron/steels but also in a wide variety of other applications such as hydrogen-absorbing alloys, batteries, magnets, and superconductive materials. These metals are desired to be recovered from so-called secondary resources from the standpoint of stable supply. Furthermore, it in necessary to treat industrial drainage and the like to remove the metals contained therein in slight amounts. Thus, the establishment of an efficient metal recovery technique is an important subject also from the standpoint of environmental protection.
One of the elemental techniques for the recovery and purification of transition metals is the solvent extraction method. The solvent extraction method has conventionally employed an acid, basic, or neutral extracting agent according to the composition of the solution to be treated. Besides being used alone, transition metals have recently come to be used as composites and similar materials such as alloys and mixtures. It is hence thought that the solvent extraction method comes to be utilized increasingly.
There is a desire for an extracting agent which has higher extraction capacity, higher extraction rate, and higher selectivity and is harmless and inexpensive.
An object of the present invention is to provide an extracting agent for a transition metal which has a novel structure entirely different from the structure of any known extracting agent for a transition metal and has excellent extracting performance.
Another object of the present invention is to provide a method for extracting a transition metal with the extracting agent.
The present invention addresses these and other shortcomings in the prior art by providing macrocyclic compounds for use in specific metal ion binding. The invention concerns a class of novel macrocycles, termed triazatrinaphthyrins, and their metal complexes and salts. In a general and overall sense, the novel triazatrinaphthyrin compounds of the present invention include those with structures in accordance with general Formula I: 
or a solvate, hydrate, ester or salt thereof; wherein R1-R3 and Ra, Raxe2x80x2, Raxe2x80x3, Rb, Rbxe2x80x2, Rbxe2x80x3, Rc, Rcxe2x80x2, Rcxe2x80x3, Rd, Rdxe2x80x2 and Rdxe2x80x3 are as defined below.
These and other objects of the present invention are accomplished by a composition for extracting a transition metal which comprises as an active ingredient a triazatrinaphthyrin or a salt thereof.
Furthermore, these and other objects of the present invention are accomplished by a method for extracting a transition metal which comprises extracting a transition metal with the above-described composition for extracting a transition metal.